Sunday, October 25, 2009

Meteor, Meteoroid, Meteorite: What's the Difference?

It wasn't until I took my first astronomy class in college that I learned that a meteor, meteoroid, and meteorite are not the same thing. Previously I had supposed that "meteor" was short for the word "meteorite," which to me was simply a rock from outer space. I also speculated that the term "meteoroid" was a sort of geeky nickname for the same rocks, since adding "oid" to the end of any word makes it sound like it's associated with little green men from a distant planet. While it is true that all three terms refer to a space rock, they can not be used interchangeably. Each term has it's own specific meaning and appropriate usage.

Firstly, the website Solar Views explains that the term meteoroid is reserved for matter in outer space which revolves around our sun. Of course, however, not everything that revolves around the sun is a meteoroid. "
A meteoroid is matter revolving around the sun or any object in interplanetary space that is too small to be called an asteroid or a comet. Even smaller particles are called micrometeoroids or cosmic dust grains, which includes any interstellar material that should happen to enter our solar system," reads the site.

Though this explanation makes sense, it raises the question, "what's an asteroid?" The website explains, "A meteoroid is anything from the size of a grain of sand up to a boulder. Anything bigger than that is considered an asteroid. "

OK, now what is a meteor? Well, the term "meteor" actually refers to the reaction that occurs when a falling meteoroid passes through Earth's atmosphere. The website Space Today explains that, "Meteors are the streaks of light associated with the burning of small chunks of rock or interplanetary debris [meteoroids] as they arrive in Earth's atmosphere from space." Just to clarify, the actual space rocks/debris are the meteoroids, and when they contact our atmosphere, they create meteors. "A sky-watcher under a dark clear sky might see a few [meteors] per hour on an average night. On the other hand, during one of the annual meteor showers, a sky-watcher might see up to 100 per hour," reads Space Today.

Now come the meteorites. According to Space Today, "A meteorite is a meteoroid large enough to survive the fall to Earth's surface." Basically, space debris can only be meteoroids while they are in outer space. Once they touch Earth's soil, they technically become meteorites.

File:Meteoroid meteor meteorite.gif

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